1. Field of the Invention
The invention relates to a fuel cell system and a method for detecting the status of a fuel cell.
2. Description of the Related Art
Fuel cells are devices for obtaining electrical energy typically by using hydrogen and oxygen as fuel. Since these fuel cells are superior in terms of the environment and are able to realize high energy efficiency, their development is proceeding in a wide range of fields for use as an energy supply system of the future. In particular, since polymer electrolyte fuel cells operate at a comparatively low temperature among the various types of fuel cells, they have good startability. Consequently, research on these fuel cells is proceeding actively for applications in numerous fields.
In a polymer electrolyte fuel cell, a membrane electrode assembly (MEA) is interposed between separators. In the MEA, an anode is provided on one side of an electrolyte membrane composed of a solid polymer electrolyte having proton conductivity, and a cathode is provided on the other side of the electrolyte membrane.
The status of a fuel cell changes according to operating conditions and the like. Therefore, technologies have been developed for monitoring decreases in cell voltage measured for each cell group in fuel cell stacks consisting of a plurality of laminated fuel cells. (see, for example, Japanese Patent Application Publication No. 2006-179338 (JP-A-2006-179338)).
However, it is difficult to accurately detect the status of a cell by simply monitoring decreases in voltage. In addition, although decreases in cell voltage can also be monitored for cell groups, it is difficult to accurately detect the status of a cell contained in the cell group. On the other hand, providing means for detecting cell voltage for each cell ends up increasing costs.